The present invention relates to a system and to a process for the sterilization of objects, particularly for the sterilization of medical instruments and accessories, by means of gas plasma, which is also called ionized gas. The gases used to produce this plasma need not have an intrinsic sterilizing ability. The sterilizing properties according to the invention result from the passage of the gas or gases through an electric field creating the plasma, which can be created, for example, by microwaves. The advantage of the invention lies in its ability to treat objects that are heat sensitive and heat labile at temperatures below 50xc2x0 C. and by using gases, which pose no danger to the operator of the system.
Sterilization processes used in hospitals have generated a good deal of controversy lately with the arrival of instruments and accessories made of heat sensitive polymer materials. Presently the autoclave is recognized as an effective means of sterilization, however with the disadvantage of requiring temperatures that are too high (above 121xc2x0 C.) to permit its use with polymer materials. Furthermore, the longterm use of the autoclave causes irreversible damages to metallic objects and irredeemably modifies some of their physical properties.
To overcome these limitations, sterilization processes using ionized gas, or gas plasma were developed. These processes operate at sufficiently low temperatures to permit the sterilization of instruments and of accessories made of heat sensitive polymer materials. However, few studies have been undertaken to determine the efficiency of these processes relative to their mechanism of destruction of microorganisms.
The use of plasma as a sterilizing agent was initially proposed at the end of the 1960""s. U.S. Pat. No. 3,383,163 describes the use of a pulsed electric field for generating an argon or nitrogen plasma, with the goal of sterilizing the internal walls of a flask. The process is such that the sterilization of the flask is directly performed during the discharge.
The interest of such a method increased with the advent of commercial sterilizers such as Sterrad(trademark), produced and sold by Johnson and Johnson, as well as, Plazlyte(trademark), produced and sold by Abtox. However, it is known that with these two types of machines, the plasma does not have a biocidal effect, but merely serves as a detoxification agent that eliminates harmful residues by limiting the oxidizing effects of hydrogen peroxide and of peracetic acid vapors injected as sterilizing agents. It may therefore be considered that those devices use gas plasmas in the sterilization process, but with the distinction that the aforementioned sterilization is achieved by the addition of chemical species and not through the action of activated plasma species.
Therefore, it would be advantageous to develop a total sterilization system and process, that employs only a low cost gas and without any risk to the operator. The gas or mixture of gases could be activated at low temperature by a plasma, then applied on the object that is to be sterilized, thereby generating biocidal species that allow for the sterilization of said object, no matter what material the object is made of.